Chlorine bleaching produces dioxins, a substance that is extremely dangerous to humans and wildlife. Dioxins are found in the atmosphere, soil, water, and in our food supply. Dioxins are linked to skin problems, cancer, reproductive problems, behavioral problems, and diabetes. Dioxins are also persistent in the environment, meaning they do not easily break down. Choosing products that have not been chlorine-bleached is preferable. Look for products that are Totally Chlorine Free or Process Chlorine Free. For more paper-buying tips, see the article "Paper-buying for individuals" on the Greenpeace website: http://www.greenpeace.org/international/campaigns/forests/solutions/paper-buying-for-individuals